This circuit can be used to harvest small amounts of electromagnetic waves in form of a voltage of about 4V though an antenna
From left to right:
Antenna: About 2m of wire were used (symbolised by the logic train oscillating)
Capacitors: 220nf 100V poly/ceramic
Diodes: 1n4148 or similar
Output Caps: 100uf 16V
Output: About 4V, depends on lenth of antenna used and the amount of electromagnetic waves avaliable in the area (symbolised by the power supply).